It is the purpose of this study to correlate the changes in plasma lipoproteins in animals fed cholesterol-rich diets with the development of accelerated atherosclerosis. The characterization of the lipoproteins induced by cholesterol feeding in dogs, swine, monkeys, rats, and rabbits has established that various species have a similar metabolic response to increased dietary cholesterol. The hyperlipoproteinemia has certain consistent features which include the occurrence of beta-very low density lipoproteins, an increase in low density lipoproteins, and the appearance of a unique lipoprotein, the HDLc. The occurrence in increased concentration of specific apoprotein (arginine-rich apoproteins) with all these cholesterol induced lipoproteins suggests an important role for this protein in cholesterol metabolism and possibly in accelerated heart disease. The various animal lipoproteins are being compared to purified human plasma lipoproteins.